The invention relates to a tangential belt drive for spinning or twisting machines having several rotating elements, which are driven by a common tangential belt, and having adjustable belt guiding members for correcting the skitting of the predetermined desired path of the tangential belt laterally or transversely of its width.
In spinning or twisting machines having a tangential belt drive, the moving direction or travel path of the tangential belt laterally of its width must be adjusted. The individual tangential belts have irregularities, for example, in the area of their connecting point, which lead to deviations from a straight moving direction. In addition, tolerances in the arrangement of the driven rotating elements and in the arrangement of belt guiding members cause deviations from the straight moving direction. In particular, in the case of long spinning or twisting machines, the adjusting of the tangential belt with respect to its moving direction is a time-consuming operation which requires considerable practical experience. This adjusting is carried out by one or several operators. In this case, it is provided that, first, the placed tangential belt moves completely freely without driving any of the rotating elements. Subsequently, the individual rotating elements are consecutively applied to the tangential belt. During this operation, the moving direction of the tangential belt is observed. If a lateral deviating of the tangential belt should occur, it is attempted to prevent this deviating by the adjusting of belt guiding members, particularly of pressure rollers. In the course of this work, it becomes necessary to newly adjust the pressure rollers repeatedly. In practice, this operation is called "wobbling-in". The whole working Process is very expensive and may last up to several hours. An additional factor is that, deviations will occur repeatedly despite a careful manual adjusting since dirt and temperature changes or the like affect the moving behavior of the tangential belt. In addition, the moving behavior of the tangential belt and thus its moving direction may change, if one or several of the rotating elements, for example, for eliminating a yarn breakage, must be stopped. In addition, the adjusting must be carried out again when, after the old tangential belt is worn out, a new tangential belt must be inserted. Deviations in the moving direction of the tangential belt result in non-uniform loading of the rotating elements and thus in an increased wear of the belt.
An object of the invention is to construct a tangential belt drive of the initially mentioned type in such a manner that an increased precision is obtained with respect to maintaining the moving direction of the tangential belt.
This object is achieved according to preferred embodiments of the invention in that several sensors are arranged along the tangential belt, which detect deviations from a given moving direction, and in that control elements are assigned to at least some of the belt guiding members, which are each controlled by an analyzing device which processes the signals of the sensors.
In this manner, the tangential belt drive is provided with a control device by means of which the adjusting of an ideal belt moving direction takes place automatically. An adjusting of the moving direction of the tangential belt no longer has to be carried out by the operator, so that considerable time is saved during mounting.
In a first embodiment of the invention, it is provided that an analyzing device is assigned to each sensor and to each control element. The control element with its control device will then operate independently in the area of its influence. In this case, it is advantageous for the sensor to be arranged in moving direction of the tangential belt downstream of the belt guiding member controlled by it. As the result, the sensor can immediately examine the success of the correction initiated by it of the adjustment of the belt guiding member.
In another embodiment of the invention, it is provided that several or all sensors and control elements of one side of the machine are connected to a common analyzing device. This common analyzing device can then carry out a coordination of the adjustments over a larger machine section or even over the whole side of the machine.
In a further development of preferred embodiments of the invention, devices are provided for the switching-off of the analyzing device and/or of the control elements and/or of the sensors during the startup of the spinning or twisting machine. In this case, the machine starts up with the adjustment of the belt guiding members which they had when the machine was switched off. By means of tis switching-off, the situation is taken into account that, during the start-up, forces may occur which may lead to a deflection of the tangential belt and which deviate far from the conventional forces during the normal operation. Thus, an overreaction of the control device is avoided during the start-up.
It was known from German Published Examined Application (DE-A) 1 510 840 to provide a control device for a tangential belt drive, by means of which the pressure force of the tangential belt against the rotating elements to be driven can be adapted to the performance requirement, i.e., to the belt speed. However, this does not affect the moving direction of the tangential belt.
It is also known (JP-A 62-250231) to assign a tension detector to the tangential belt of a tangential belt drive which, by means of a corresponding control device, controls a tensioning device and thus automatically readjusts the belt tension. This device also does not affect the moving direction of the tangential belt.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.